causes any application to flash in the taskbar. Unfortunately, htas are processes, not applications. Open an hta then press Ctrl + Alt + Del and you'll see your hta under Processes (mshta.exe), not Applications.

AppActivate() takes either the app title or the process id. This will give AppActivate() the process id:

After all that, it can't distinguish between multiple instances of the hta and it doesn't flash the hta in the taskbar. It brings the hta to the top. I have created an incredibly complex alternative to window.focus().

On an unrelated but more positive note, Win32_Process exposes lots of properties [msdn.microsoft.com]